The earliest attempts at fusion reactor design used magnetic confinement to compress the fuel plasma as well as keep it away from the reaction vessel walls. The best such designs were derived from the Russian tokamak toroidal reactors. Newer attempts use inertial confinement (like H-bomb secondaries) and have come much closer to break-even than tokamak types have. No magnetic fields are used here.
Downsizing is not going to help, the largest yet, JET, has only given a very short pulse of fusion. The requirement is to upsize it, and this will be ITER. You can find this in Wikipedia.
When the core of a protostar has reached about 10 million K, pressure within is so great that nuclear fusion of hydrogen begins, and a star is born.
A, the Sun; B, the hydrogen bomb; C, Fusion [tokamak] reactors - not to be "functional" until 2040. _________________________________________________________________
If it is a tokamak as is likely, the chamber will be under vacuum, unlike a pressurised water reactor which has a pressure vessel at high pressure. However a fully engineered design does not exist yet so what the plant to absorb the reaction's heat will look like is unknown.
What is the Tokamak Fusion Reactor?
Tokamak
A tokamak is the magnetic container that traps and holds the plasma in this type of physics.
tokamak
You think probable to Russian installation Tokamak.
In tokamak reactors, approx 300 million degC
Plasma is highly ionized atoms. This results in extremely energetic ions, and these ions carry an electrostatic charge. The tokamak is a container with magnetic fields for boundaries. The plasma is a moving group of electrostatic charges, and moving charges create magnetic fields. The magnetic field thus created interacts with the magnetic field set up in the tokamak to deflect and thus confine the charged plasma.
W R. Spears has written: 'A pulsed tokamak reactor study'
Ingeborg Entrop has written: 'Confinement of relativistic runaway electrons in tokamak plasmas'
You don't give the list of 'following countries' ! However I believe the largest or most powerful tokamak so far is the JET at Culham in England. See link below. The new one in S Korea looks perhaps to surpass that but it has not yet been fully operated. The tokamak originated in Russia, it was a brilliant development which took western science by surprise, but is now pretty universal in fusion research. The other possible lead is by laser ignition which is being promoted in a few places, but is very difficult to set up accurately. There is a Wikipedia article on 'tokamak' which gives a long list of facilities in many countries.
A Tokamak reactor uses strong magnetic fields to contain the fusion reaction. While significant progress has been made in the field of fusion, temperatures high enough for continuous fusion have not been sustained for long periods of time. (Chemistry: Matter and Change; book)
S. P Hirshman has written: 'Two-dimensional transport of tokamak plasmas' -- subject(s): Tokamaks